"""Add unique constraint on audio_versions.nc_file_path.

Prevents duplicate imports when concurrent scans race on the same file.

Revision ID: 0009_av_nc_path_uq
Revises: 0008_drop_nc_columns
Create Date: 2026-04-12
"""

from alembic import op

revision = "0009_av_nc_path_uq"
down_revision = "0008_drop_nc_columns"
branch_labels = None
depends_on = None


def upgrade() -> None:
    # Remove any existing duplicates first (keep the oldest version per path)
    op.execute("""
        DELETE FROM audio_versions
        WHERE id NOT IN (
            SELECT DISTINCT ON (nc_file_path) id
            FROM audio_versions
            ORDER BY nc_file_path, uploaded_at ASC
        )
    """)
    op.create_unique_constraint(
        "uq_audio_version_nc_file_path",
        "audio_versions",
        ["nc_file_path"],
    )


def downgrade() -> None:
    op.drop_constraint("uq_audio_version_nc_file_path", "audio_versions", type_="unique")